When I watch downloaded videos, from a certain point on the sound is delayed.
I view my videos using WinAMp or WMP.
Do I need any additional codecs, and if so, where can I download them.
Thanks very much.

Is the delay increasing over time (i.e. being bigger the further the film goes), or constant (the same delay in the whole file)?

If it is the first, it most probably is a bad encoding, (or, less probably, that your player is not playing at the correct sampling rate).

If it is the second, then, it still is a bad encoding, but can be fixed. Media Player classic (between others), allow to speficy a delay of the audio, so you can adjust it for that specific video.
I don't know if the file can be corrected with another program.

At last, if it it is the second case, but happens from one point onwards... that might be either an error on the bitstream, or that the video has been joined in some way and is missing some part of the video, or who knows..

one of the videos I am referring to is in DVDRip.DivX-DVL format.
I think I need to get the codec for that format, do I not?
Where can I download that codec?

For DivX, i use the "old", but reliable 5.2.1 decoder: DivX521XP2K.exe, since i have some issues with the new 6.x decoders (seeking is sometimes slow etc).

Make sure your graphics card & soundcard drivers are up to date as well.

The video you are referring to is an illegally downloaded DVD rip.

Setting that aside... Don't listen to CiTay, he lives in a dream world where people use outdated and inferior decoders. Instead download the Media Player Classic and install the ffdshow decoder. Alternatively you can also try VLC, if you feel adventurous...

Sorry my old friend, but in my opinion, ffdshow is a prime example of a software that's too cluttered and not user-friendly at all, be it in configuration or in trying to find out which version to get.

And the DivX 5.2.1 decoder is not inferior. Yes, the 6.x decoder can do multithreading, but what good is it when seeking is sometimes much slower than with the single-threaded 5.2.1 decoder? If you mean "inferior to ffdshow", well, useless bells & whistles of ffdshow aside, the decoding quality is the same.

how do I know if my graphics card & soundcard drivers are up to date?
and, if I find out they're outdated, how can I update them?
thank you so much.

ffdshow is probably faster though, especially with the recent speed improvements in ffmpeg. Plus, I like the postprocessing options it has,

First find out which cards you have. It's listed in the device manager. Then go to the websites of those firms (let's say NVIDIA and Creative, for example) and download the newest drivers. If you haven't updated in more than a couple of months, usually your drivers are already outdated and you should install the new ones.

1) If you have a name-brand computer like Dell, go to the makers website and find the "support" or "downloads" area. There should be a place where you can enter your model and get a list of drivers. Keep this list open in your web browser, maybe bookmark it for future use. There should be dates and version numbers next to each driver file.

2) Right click on "My Computer", select Properties. Click the "Hardware" tab, then hit the button for "Device Manager". This gives you a list of your hardware. Find the hardware that matches the drivers available on the website. Double click on these to show the detailed properties, then click the "Driver" tab. You will see a date and version number.

3) If the date is older or the version is smaller on any hardware, download and install the driver for that hardware.

4) If you have any hardware that you added yourself, do the same thing at the website for the manufacturer of that hardware.

You could also do the process in reverse by looking at the Device Manager first, but there is a lot of hardware that doesn't have drivers that get updated as such. Note that your video card is under "Display Adapters" and the sound card is under "Sound, video, and game controllers". Another advanced note is that drivers for your video card are generally better to get directly from the chip maker (ATI, Intel, or Nvidia) unless you have a laptop. So if you know what make and model of video card you have you could try that method...

Re: OP, I used to have the same delay. But it's the other way around. The audio comes faster than the video. Strangely, it happens only if I play the file using WMP. Then I use The Core, the audio and the video are nicely synchronized.